Positive latch for two-lid egg cartons

ABSTRACT

The invention relates to a latch for a two-lid egg carton. The latch comprises a flap which extends from one lid across the other lid and cooperating latching means provided on the flap and on the other lid. The cooperating latching can be: A hole provided in the flap and a projecting button on the other lid which extends through the flap hole or a pair of ears are provided on the flap which are wedged into a corresponding recess on the other lid or are snapped into an opening provided on the other lid. The ears, recess or opening latching means can be used as a supplementary latching means in combination with the button and hole or can be used as the sole latching means.

United States Patent David C. Trimble Yorklyn, Del.

Nov. 29, 1968 Jan'. 19, 1971 Haveg Industries, Inc. Wilmington, Del.

a corporation of Delaware [72] Inventor [2l Appl. No. [22] Filed [45] Patented [73] Assignee [54] POSITIVE LATCH FOR TWO-LID EGG CARTONS 20 Claims, 12 Drawing Figs.

51 Int. Cl 865d 5/66,

501 FieldofSearcli ..229 44,45,

Primary Examiner-David M. Bockenek Attorney-Sheldon F. Raizes ABSTRACT: The invention relates to a latch for a two-lid egg carton. The latch comprises a flap which extends from one lid across the other lid and cooperating latching means provided on the flap and on the other lid. The cooperating latching can be: A hole provided in the flap and a projecting button on the other lid which extends through the flap hole or a pair of ears are provided on the flap which are wedged into a corresponding recess on the other lid or are snapped into an opening provided on the other lid. The ears, recess or opening latching means can be used as a supplementary latching means in combination with the button and hole or can be used as the sole latching means.

PATENTEUJANISIHYI 3 sum 1 nr 3 VII". ar I I l/I'l DAVID c. TRIMBLE v INVENTOR.

ATToamg PATENTEUJANIQIQTI 3.556387 sum 2 or 3 DAVID C. TIZ IMBLE 1 VENTOR.

ATTORNEY PATENTEUJANIQIQYI v 3556387 sum 3 or 3 DAVID C. TQIMBLE.

INVENTOR ATTORNEY There has been a search for a latch for a two-lid carm u.s. Pat N'osISQI 9'1 .844 and 3,362,606 each Show a fric- Y tion latch'which'provides for a wall of each lid to be wedged between slots inposts and relyingupon friction holding the lids in closed position. {Thistype latchihasproven to be commercially unsatisfactory since the amount of latching is inadequate. A tab and slot latch isproposed in U.S. Pat; No. 2,423,756. However, the construction of this patent has its drawbacks since thetabs 24'must befof stiff material to keep from curling under when the tabs strike the'eggs during closing. Furthermore; as can be seen from the length of the tab 24 in FIG. 7 interference by the eggs during closing is a tremendous problem. Also, the tabs 24 can be wedged out of the position shown in FIG. 1 during nesting or stacking resulting in the misalignmentbetween the tabs and slots 25 which is a serious problem when sent through anautomated closure.

Accordingly, it isan" object of this invention to provide two-lid egg cartonwith a positive mechanical latch.

It is a particular object to provide a'positive mechanical latch for eggf'oa'rtons made from materials of various stiff- -ne'sses as for instance, foam plastic egg cartons, molded pulp egg cartons and solid plastic egg cartons.

Other objects of the invention will become appa'rent from the following description with reference to. the drawing wherein: V I FIG. 1 is a perspectiveview of an eggcarton. illustrating one embodimentofthe'invention; :1 1 u- FIG. 2.is a section 'view along section line 2-2 ofFlGQl; F [G3 is an isolated top 'view ofa flap shown in FIGS. 1 and FIG.;'4 is an isolated top view' o fa'button and surrounding recessshowninFIGS.land 2;

- no. Sis'as'etidtt viewalo'ng sectionlinehS-S of Fla. 1

FIG. 8 is a partial top view illustrating another modification ofthe embodiment of FIG. I; v

FIG. 6 is a partial'section'viewsiniilar'to FIG.2 illustrating a FIG. 9 is aview' of an egg carton illustrating another embodiment of the invention;

FIG. 10 is a'view of an egg'ca'rton illustrating another embodirnent'of the invention,

FIG. 11 is a top view of a flap illustrated in FIG l; and 7 FIG. 12 is a section view along'section line 12'- I2 of FIG. 10, Referring-to FIGS. l-;'there is illustrated an egg carton comprising an egg tray bottom 12 and a pair of lids l4 and 16 7 each pivotally connected totto the tray at longitudinally extending hinge lines 18 and 20, respectively. The lid 14 comprises a sidewall 22 extending from the hinge line .18 and transversely to a planar top wall and the planar wall 24 extends to a sidewall-26 at the free end of the lid which lies in a plane transverse to the-planariwall 24. The lid 16 comprises a sidewall 28 extending from the hinge line and transversely to a planar top wall30 and the planar wall 30 extends to a sidewall 32 at the free end of the lid which lies in a plane transhas a pair of ears 38 and 40 at the'free end thereof andan opening 42 therein. In the latched position, a button projection 44 ektends upwardly from a flap receiving recess 46 in planar wall 30 through the opening 42 of the flap and the recess 46 located on the wall 30 receives the flap 34 therein. A depression 48 is provided in thelid l6to provide access for ones finger to disengage the flap 34. When the lids I4 and 16 are in closed position as shown in FIG-.2 the sides 26 and 32 engage each other with the free end edge 50 and 52, respec tively, bearing on a center post 54. The cells andpost structure of the egg tray. l2may be constructed in any well-known manner, for instance, as shown'in any of the U.S. Pat. Nos.

The flap 34 is cut out of the sidewall 26 and; is the same Iengthas thevertical length figure. (figure 2) of the wall 26. The hinge line 36 is provided at the upperportion of the wall 26,;atthe juncture of walls -24 and 26 whereby the flap is pivoted about the hinge line 36 for into alatching position or I .beyond. When they flap is pivoted beyond the plane of top wall 24, the resilient nature of the hinge 35 36 is such that the flap willtendto pivot back towards the wall 26. This resilient nature of the hinge 36 helps maintain the button 44 in'the opening 42 whenltheflap 34 is in latched position.

Ears 38and 40 are provided on the flap 34 and'corresponding ear receiving recesses 56 and 58 are provided in the flap receiving recess 46 'to provide additional latching assurance.

Referring in particular to FIGS. 389d 4. the flap receiving recess? 46 on the top wall 30 of cover 16 is of essentially the same shape as the flap 34 and comprises atop wall 47 offset or depressed from the .main plane of. the top wall 30 a distance slightly greater than .the thickness of flapj34. However, the distance d between the ends of. the ear receiving recess portions 56 and 58is less than the distance D between the ends of the cars 38 and 40 so that the free end .of the latch 34 will have to be wedged into the corresponding end portion of the recess responding edges 68,and.70 of the ear receiving recesses 56 and $8, respectively,;to hold the free end of the flap in place to assure return of the flap34 to its latched position should the flap and button become disengagedfIhe-flap-will buckle tending to raise the flap relative to the button 44 and if the flap disengages fromthe button 44, theflap will return back to its prior latching condition with the button upon release of the squeezing pressure since the free end of the flap has remained in place As soon as the squeezing pressure is released,the flap will regain its prior latched position. If there is any lateral racking" action of thelids insimultaneous opposite direction as shown by arrows C-D (FIG. l). the edge 76 of the flap ad and edge- 78 of the recess will engage to prevent any significant relative lateral movement; between the lids. If the racking" actionis in the opposite direction of the arrows CD, then the edges 72 and 74 will cooperate to ,prevent any significant relative movement between the lids.

The dimensions between the opening 42, button 44, edges 80 and 82 of the flap 34 and shoulders 60 and'62 of the recess 46 are such that any tension imposed on the flap 34 by forces tending to open the lids will be shared by the edges and 82 of the ears 38 and 40, respectively, bearing on shoulders 60 and 62. respectively, and the edge of opening 42 bearing on the button 44.'Depending upon tolerances, the edge of opening 42 may deform slightly under load before a force will'be 6 applied to the ears 38 and 40 or vice versa. It should be realized that upon any tendency of the lids to open, the lids pivot away from each other and therefore the flap 34 andsurface 30 tend'to move in opposite directions with the button'44 and recess walls 60, 62 placing the flap '34 in tension. Therefore even if the carton is turned upside down, the weight of the eggs will tend to open the lids l4 and 16 but at the same time place flap 34 in tension whereby the flap is held in latched position. I

-An additional, but not necessary, method for maintaining the flap 34 is latched latched position is to place the flap in tension while in latched position. This can be accomplished by bowing the walls 26 and 32 in opposite directions whereby when the lids are in the position of FIG. 2, and a tray such as that shown in U.S. Pat. No. 2,446,264 is used, the lids will be biased away from eachother placing the flap in tension.

Referring to FIG. 6 a modification of FIG. I is shown. The same reference numerals are utilized to designate the same elements in FIG. l5 only an a is affixed thereto. An undercut 102 is provided in the button 440 and the opening 420 is located on the flap 34a so the portion 104 of the opening 42a fits into the undercut 102. The undercut provides an additional feature against accidental unlatching due to squeezing, racking or any other force tending to lift the flap 34a away from latching'position. An alternative to the undercut is to back draft or slant the surface of the post engaging edge 104 from the top of the button 44a to the recess 46 in a direction away from the free end of the lid or the whole button may be slanted in the same direction.

Referring to FIG. 7, there is a illustrated another modification of FIG. 1, The same reference numerals are utilized to designate the same elements in FIGS. I'5 only a b is affixed thereto. In this embodiment. the ears are left off andthe latch is provided by the button 44b and opening 42b in the flap. The edges 72b, 74b, 76b, and 78b cooperate to minimize racking." Obviously, the edge of the opening 42b will have to be located immediately adjacent or contiguous the button 44b in order that tension will be almost immediately applied to the flap upon any opening force being applied to the lids. Furthermore, if desired, the walls corresponding to walls 26 and 32 in FIG. 2 can be bowed as described above to place the flap in tension during latched position.

Also, if desired, the opening 42b may be necked or in the form of an ellipse with the dimension of the necked portion or the smallest dimension of the ellipse being slightly smaller than the corresponding dimension of the button 44b. In this case, the shortest radius of the ellipse or the dimension of the neck portion will extend in the longitudinal direction. The edge of the opening at the smallest dimension will frictionally grip the button 44b to resist disengagement of the flap from the button in case of a squeezing action being applied to the lids. Also, the undercut disclosed in FIG. 6 or a slanted post can be utilized in this embodiment.

Referring to FIG. 8, there is illustrated another embodiment of FIG. I, The same reference numerals are utilized to designate the same elements in FIGS. 1-5 only a c is affixed thereto. The button and opening therefor has been eliminated. The ears and ear receiving recess perform the sole latching function with edges 80c, 60c, 82c, and 62c, taking any force tending to open the lids.

The stiffness of foam plastic varies. If foam of high stiffness or molded pulp or a solid plastic is used wedging of the ears 38c and 40c into the ear receiving recess is more effective. However, if a stiff material is used, the dimensions D and d, as shown in FIGS. 3 and 4, can be approximately the same whereby the ears 38c and 40c are not wedged into the ear receiving recesses. The stiff material will perform almost as well as if the ears were wedged which is more or less required with relatively soft material. Obviously, a stiff material can be used in any of the preceeding embodiments of FIGS. 1, 6, and 8.

FIG. 9 is another embodiment of FIG. 1, The same reference numerals are utilized to designate the same elements in FIGS. l-S only a e is affixed thereto. The button and opening therefor has been eliminated. An opening 202 is provided through which the flexible free end of the flap 34d is tucked whereby the ears 38d and 40d snap past the edge of opening 202 to become lodged under the wall 30d to prevent the flap from being dislodged from latching position. The ears 38d and 40d bear on the edge 204 of the opening to take any force tending to open the lids. Obviously, openings could be provided just for the ears 38d and 40d with the opening 202 closed in the same manner as surface 48 in FIG. I.

Referring to FIGS. [-12, another modification is illustrated. The same reference numerals are utilized to designate the same elements in FIGS. l only an e is affixed thereto. A strap or flap 302 is secured to the top wall 24c by any suitable means such as an adhesive or, as shown, by a pair of staples 304. The flap may be made out of any flexible material such as polypropylene. The flap comprises a neck portion 306 and a pair of ears 308 and 310 at the free end thereof. An opening 312 is punched in the wall 28a. The tab portion 314 ofthe wall which was punched out to provide the opening 312 is left attached at the hinge line 202 for aesthetic purposes and keeping the inside of the carton clean.

The width between the ends of the ears 308 and 310 is greater than the corresponding width of the opening 312 and the width of portion of opening 312 corresponding to a the neck 306 is approximately the same as the width of the neck portion 306. In closing the carton, the flap is placed on top of the wall 30a and is bent downwardly at the neck portion 306 and since the flap 302 is flexible, the flexible ears 308 and 310 snap past the edge of the opening 312 to assume a latched position. Any force tending to open the lids will be resisted by the edge ofthe ears 308 and 310 at the neck portion 306 bearing on the corresponding edge portion of the opening 312.

I claim: I

I. An egg carton comprising: An egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said latching flap comprising an opening therein; latching means carried by said other lid surface means comprising a button projecting upwardly therefrom and extending through said opening when said flap is in latched position to hold said lids in closed position whereby the edge of said opening and said button will coact to resist opening of said lids when said flap is in latched position and said flap is placed in tension when an opening force is applied to said lids.

2. An egg carton comprising: An egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said latching flap comprising at least one ear extending in a longitudinal direction therefrom; latching means carried by said other lid surface means comprising at least a recessed portion conforming in shape to said at least one ear and the corresponding portion of said flap from which the ear extends;

said ear and corresponding portion of said flap from which the ear extends being received in said recessed portion when the flap is in latched position whereby said ear and its corresponding portion of said recessed portion con coacts to resist opening of said lids and said flap is placed in tension when an opening force is applied to said lids.

3. An egg carton comprising: An a egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said flap comprising at least one ear extending in a longitudinal direction therefrom; latchingmeans carried by said other lid surface means comprising an opening; said opening, the ear and the portion of said flap from which the ear extends being so proportioned and arranged that when the flap is in latched position, the ear will extend in the opening beyond the boundary of the opening under the surface means of said other lid and coact with the edge of the opening to resist opening of said lids whereby said flap is placedin tension when an opening force is applied to said lids.

pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position ex tends in a direction transverse to the longitudinal edges and a substantialportion thereof engages said outer surface means of the other of said lids; and latching. means carried by said latching flap and latching means carried by said other lid surface means cooperating with said latching flap means when said flapis in latched position to hold said lids in.closed position; said cooperating latching means being so constructed and arranged relative to each other to provide a positive mechanical interlock when said flap is in latched position whereby said flap is placed in tension when an opening force is applied to said lids; said other lid having a recess in said surface means thereof receiving the entire flap therein when said flap is inlatched position; said recess including a pair of longitudinally spaced walls; said longitudinally spaced walls and the correspondingedges of said flap being closely adjacent each other to resist substantial relative longitudinal movement between saidlids.

5. The structure as recited in claim I wherein there is an undercut in the portion of said button which coacts with the edge of sad said opening to resist opening of said lids; at least a por- ,the flap is in latched position.

latching means carried by said other lid surface means further comprises an opening; said opening, the ear and the portion of said flap from which the ear extends being so proportioned that when the flap is in latched position, the ear will extend in the opening beyond the boundary of the opening under the surface means of said other lid and coact with the edge of the opening to additionally resist opening of said lids and to prevent the edge of said flap opening and said button from being dislodged from a latching position.-

8. The structure as recited in claim 7 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall one edge of which is said free edge; and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said opening carried by the other lid surface means being on the planar top wall thereof. I

9. The structure as recited in claim 8 wherein the pivotal connection of said flap to said one lid is generally at the juncture of said second sidewall and said planar top wall.

10. The structure as recited in claim 3 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge; and a planar top wall thelongitudinal edges of which join the other longitudinal edges of said lid sidewalls; a said opening carried by the other lid surface means being on the first sidewall.

ll. The structure as recited in claim l0 wherein said latching means carried by said flap comprises a pair of ears which extend in opposite longitudinal directions from opposite sides of the free end of said flap.

'12. The structure as recited in claim 4 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray a second sidewall oneedge of which is said freeedge; and a planar top wall the longitudinal edges of which join theother longitudinal edges of said lid sidewalls: said latching means carried, by the other lid surface means being on the planar top wall thereof; the pivotal connection of said flap to said one lid being generally at the juncture of said second sidewall and said planar top wall;and said other lid has said recess in said planar top wall thereof.

13. The structureas recited in claiml wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said latching means carried by the other lid surface'means being on the planar top wall thereof; said pivotal connection of said flap to said one lid defining an integral connection I between said flap and lid and being generally located at the juncture of said second sidewall and said planar top wall; an opening in said second sidewall of said one lid from which said flap is pivoted; said button is located on said top wall of said other lid; the portion of the surface of said button coacting with the edge of said opening is from the uppermost portion of the button toward the top wall of said one lid slanted in a direction toward said first lid. e

14. The structure as recited in claim I wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge, and a planar top wall, the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said button being on the planar top wall of said other lid; the pivotal connection of said flap to said onelid being generally at the juncture of said second sidewall and said planar top wall. r a

15. The structure asrecited in claim 14 wherein an opening is in said second sidewall of said one lid from which said flap is pivoted.

' 16LThe structure as recited in claim 15 wherein said other lid has a recess in said planar top wall thereof receiving the entire flap therein; the walls of said recess and the corresponding edges of said flap being arranged to engage each other to resist substantial relative longitudinal movement between said lids.

17. The structure as recited in claim I wherein said latching means carried by said flap further comprises at least one ear extending in longitudinal direction therefrom and said latching means carried by said other lid surface means further comprises a recessed portion; said ear and corresponding portion of said flap from which the ear extends being received in said recessed portion when the flap is inlatched position; said recess portion being so shaped that said ear and its corresponding portion of said recessed portion coacts to additionally resist opening of said lids.

18. The structure as recited in claim 17 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewalL one edge of which is said free edge; and a planar top wall, the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said button and said recessed portion being on the planar top wall of said other lid; the pivotal connection of said flap to said one lid being generally at the juncture of said second sidewall and said planar top wall.

19. The structure as recited in claim 18 wherein an opening is in said second sidewall of said one lid from which said flap is pivoted.

20. The structure as recited in claim 18 wherein said recess receives the entire flap therein when said flap is in latched UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,556. 387 Dated January 19, 1971 Inventor-( David C- Trimble It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 53 omit tot Column 2, line 9 omit 35 Column 2, line 45 omit ad Column 2, line 70, is latched latched should read in latched Column 3, line 60 e should read d In the Claims Claim 5, line 40 omit sad Also in lines 40 and 41, omit at least a portion of the edge of said opening of said lids;

Claim 6, line 46, insert between said recessed the following flap and said ears are wedged into said Claim 16, line 51 reference to Claim 15 should read Claim 14 Signed and sealed this 11th day of May 1971.

(SEAL) Attest:

EDWARD M.FIETCHER,JR. WILLIAM E. SCHUYIER,JR.

LArttesting Officer Commissioner of Patents 

1. An egg carton comprising: An egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said latching flap comprising an opening therein; latChing means carried by said other lid surface means comprising a button projecting upwardly therefrom and extending through said opening when said flap is in latched position to hold said lids in closed position whereby the edge of said opening and said button will coact to resist opening of said lids when said flap is in latched position and said flap is placed in tension when an opening force is applied to said lids.
 2. An egg carton comprising: An egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said latching flap comprising at least one ear extending in a longitudinal direction therefrom; latching means carried by said other lid surface means comprising at least a recessed portion conforming in shape to said at least one ear and the corresponding portion of said flap from which the ear extends; said ear and corresponding portion of said flap from which the ear extends being received in said recessed portion when the flap is in latched position whereby said ear and its corresponding portion of said recessed portion con coacts to resist opening of said lids and said flap is placed in tension when an opening force is applied to said lids.
 3. An egg carton comprising: An a egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; latching means carried by said flap comprising at least one ear extending in a longitudinal direction therefrom; latching means carried by said other lid surface means comprising an opening; said opening, the ear and the portion of said flap from which the ear extends being so proportioned and arranged that when the flap is in latched position, the ear will extend in the opening beyond the boundary of the opening under the surface means of said other lid and coact with the edge of the opening to resist opening of said lids whereby said flap is placed in tension when an opening force is applied to said lids.
 4. An egg carton comprising: An egg receiving bottom tray comprising a pair of spaced longitudinally extending sidewalls; a pair of lids each comprising outer surface means terminating at an inner longitudinal edge and a free longitudinal edge; each lid being pivotally connected at its said inner longitudinal edge to a respective one of said sidewalls whereby the lids can pivot in a direction toward each other into a closed position covering said tray; a latching flap pivotally connected to one of said lids and when the lids are in said closed position extends in a direction transverse to the longitudinal edges and a substantial portion thereof engages said outer surface means of the other of said lids; and latching means carried by said latching flap and latching means carried by said other lid surface means cooperating with said latching flap means when said flap is in latched Position to hold said lids in closed position; said cooperating latching means being so constructed and arranged relative to each other to provide a positive mechanical interlock when said flap is in latched position whereby said flap is placed in tension when an opening force is applied to said lids; said other lid having a recess in said surface means thereof receiving the entire flap therein when said flap is in latched position; said recess including a pair of longitudinally spaced walls; said longitudinally spaced walls and the corresponding edges of said flap being closely adjacent each other to resist substantial relative longitudinal movement between said lids.
 5. The structure as recited in claim l wherein there is an undercut in the portion of said button which coacts with the edge of sad said opening to resist opening of said lids; at least a portion of the edge of said opening of said lids; at least a portion of the edge of said opening is disposed in said undercut when the flap is in latched position.
 6. The structure as recited in claim 2 wherein a pair of ears are provided which extend in opposite longitudinal directions from opposite sides of the free end of said recessed portion.
 7. The structure as recited in claim l wherein said latching means carried by said flap further comprises at least one ear extending in a longitudinal direction therefrom and said latching means carried by said other lid surface means further comprises an opening; said opening, the ear and the portion of said flap from which the ear extends being so proportioned that when the flap is in latched position, the ear will extend in the opening beyond the boundary of the opening under the surface means of said other lid and coact with the edge of the opening to additionally resist opening of said lids and to prevent the edge of said flap opening and said button from being dislodged from a latching position.
 8. The structure as recited in claim 7 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall one edge of which is said free edge; and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said opening carried by the other lid surface means being on the planar top wall thereof.
 9. The structure as recited in claim 8 wherein the pivotal connection of said flap to said one lid is generally at the juncture of said second sidewall and said planar top wall.
 10. The structure as recited in claim 3 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge; and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; a said opening carried by the other lid surface means being on the first sidewall. ll. The structure as recited in claim 10 wherein said latching means carried by said flap comprises a pair of ears which extend in opposite longitudinal directions from opposite sides of the free end of said flap.
 12. The structure as recited in claim 4 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall one edge of which is said free edge; and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said latching means carried by the other lid surface means being on the planar top wall thereof; the pivotal connection of said flap to said one lid being generally at the juncture of said second sidewall and said planar top wall; and said other lid has said recess in said planar top wall thereof.
 13. The structure as recited in claim l wherein said surface means of each lid comprises a first sidewaLl, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge and a planar top wall the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said latching means carried by the other lid surface means being on the planar top wall thereof; said pivotal connection of said flap to said one lid defining an integral connection between said flap and lid and being generally located at the juncture of said second sidewall and said planar top wall; an opening in said second sidewall of said one lid from which said flap is pivoted; said button is located on said top wall of said other lid; the portion of the surface of said button coacting with the edge of said opening is from the uppermost portion of the button toward the top wall of said one lid slanted in a direction toward said first lid.
 14. The structure as recited in claim l wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge, and a planar top wall, the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said button being on the planar top wall of said other lid; the pivotal connection of said flap to said one lid being generally at the juncture of said second sidewall and said planar top wall.
 15. The structure as recited in claim 14 wherein an opening is in said second sidewall of said one lid from which said flap is pivoted.
 16. The structure as recited in claim 15 wherein said other lid has a recess in said planar top wall thereof receiving the entire flap therein; the walls of said recess and the corresponding edges of said flap being arranged to engage each other to resist substantial relative longitudinal movement between said lids.
 17. The structure as recited in claim l wherein said latching means carried by said flap further comprises at least one ear extending in longitudinal direction therefrom and said latching means carried by said other lid surface means further comprises a recessed portion; said ear and corresponding portion of said flap from which the ear extends being received in said recessed portion when the flap is in latched position; said recess portion being so shaped that said ear and its corresponding portion of said recessed portion coacts to additionally resist opening of said lids.
 18. The structure as recited in claim 17 wherein said surface means of each lid comprises a first sidewall, one longitudinal edge of which is said inner edge pivotally connected to the sidewall of said tray; a second sidewall, one edge of which is said free edge; and a planar top wall, the longitudinal edges of which join the other longitudinal edges of said lid sidewalls; said button and said recessed portion being on the planar top wall of said other lid; the pivotal connection of said flap to said one lid being generally at the juncture of said second sidewall and said planar top wall.
 19. The structure as recited in claim 18 wherein an opening is in said second sidewall of said one lid from which said flap is pivoted.
 20. The structure as recited in claim 18 wherein said recess receives the entire flap therein when said flap is in latched position; said recess including a pair of longitudinally spaced walls; said longitudinally spaced walls and the corresponding edges of said flap being closely adjacent each other to resist substantial relative longitudinal movement between said lids. 